21 Dec 2021

Engaging With PIR Benefits Assists Drive for Housing Stock's Future Sustainability


Heat escape from poorly-insulated homes is a known contributor to excess CO2 emissions. It’s a serious issue that needs urgent address if the UK government is to attain its net-zero target and put our built environment on a long-term sustainable footing.


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For housebuilders, going ‘above and beyond’ required energy standards will be key to futureproofing a property’s performance and negating the need for potentially costly, energy-profligate refurbishment. Adopting Passivhaus principles, which include using high levels of quality insulation within a building’s fabric, eliminates heat loss to create a construction with low environmental impact.

Ideally, this type of precision design and implementation in terms of the fabric’s material make up would be seen as standard building practice in the UK. One day it might be so, particularly if property owners are minded to demand more from their home’s thermal performance in order to reduce its carbon footprint. By focusing on the insulative composition of a property’s walls, floors and roofs, housebuilders can help fulfil that requirement.

What makes PIR a reliable investment in terms of insulation?

Polyisocyanurate (PIR) panels offer two key benefits when specifying insulation for a house built using Passivhaus principles: low thermal conductivity and durable performance. Such properties are a prerequisite for the creation of an airtight construction containing comfortable interiors.

There are other issues to consider when it comes to the insulation selection process. Insulation thickness needs to be decided based on the proposed elemental detail and U-value target. This will also inform whether the building’s design needs to be altered in order to accommodate the panels’ width. The insulation’s durability, lifespan and useability – which can impact site hours and labour costs and in-turn, a project’s sustainability – are also to be taken into account at the design stage.

There are numerous benefits associated with PIR insulation. Its closed-cell structure means it has limited water absorption potential, allowing the thermal performance and reliability of the product to be retained over time. When it comes to installation, the PIR boards are lightweight, less cumbersome to transport and easy to cut. Unlike its fibrous counterpart, PIR doesn’t shed fibres – which can be inhaled – and causes less irritation whilst being handled. This results in a more comfortable application for installers whilst the improved performance reduces energy use, thus benefiting the environment over the lifetime of the property.

Specifying VIP insulation for flat roofs and terraces

With a lambda value as low as 0.022 W/mK, the vacuum insulation panel (VIP) – a premium solution – provides excellent performance. This, coupled with its slim composition, means it requires less space to achieve the same U-value as other insulation materials. This is of particular benefit to housebuilders looking to maximise interior living space in multi-property developments with limited plot size. It also helps overcome challenges involved with insulating flat roofs and roof terraces where insulation build-up is an issue. In some cases, VIP panels offer a thermal performance of the core of lambda 0.006 W/mK; a greater insulation outcome that is achieved with a much thinner solution.

It is always recommended to have a site survey carried out prior to ordering a VIP solution. Given that VIPs cannot be cut or altered on site, it is vital that dimensions are correct prior to order. This should also take into account potential obstructions or openings such as rooflight and drainage outlets, which would affect the layout of a vacuum insulation panel scheme.

As vacuum insulation panels are vulnerable to puncture, a protected VIP is recommended. If this happens the VIP’s insulation value will degrade to roughly that of a conventional PIR material. A construction site could therefore pose problems for VIPs during their handling and installation. The best solution is to utilise a VIP panel that is fully-encapsulated within a high density PIR protective shell. This provides reassurance that the product can be easily installed by the contractor, with the knowledge that the VIP’s excellent thermal insulation value will be maintained.

A contractor should always be aware of the insulation technology being used in a roof terrace scheme, particularly in relation to VIPs. They need to be aware that VIPs cannot be cut or modified on-site, which is a complete shift of mind-set from when they use conventional insulation products. Furthermore, VIP installers should always use the design layout provided.

Engaging with an insulation specialist which provides a full project design is also recommended in flat roof and terrace applications. This creates a scheme layout in conjunction with the product delivery and ensure the quantity of material delivered is optimised to eliminate or reduce site waste. It is therefore vital that the design scheme is followed precisely in order to avoid installation difficulties and product shortfall.

According to the Insulation Manufacturers Association (IMA), the average UK household spends around £1,230 on fuel bills each year which can be up to 50% more than necessary due to the lack of energy-saving measures being implemented in the home. Poorly-insulated building fabric is a major contributor to this domestic energy wastage and its negative effect on the environment. This enforces the message that it’s better to build correctly in the first instance by taking a fabric-first approach to the construction of new homes.

In this instance, the thermally-proficient, durable properties of PIR and other high-performing materials such as VIPs are absolutely ideal.


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